Hydraulic pump or motor



March 26, 1963 Y K. HENRICHSEN 3,082,696

HYDRAULIC PUMP 0R MOTOR Filed Sept. 50-, 1959 5 Sh eet s-Sheet 1 PRESSURE INVENTOR. KNUT HENRICHSEN M PM ATTORNEY March 26, 1963 K. HENRICHSEN 3,

HYDRAULIC PUMP OR MOTOR Filed Sept. 50, 1959 5 Sheets-Sheet 2 INVENTOR. KNUT HENRICHSEN ATTORNEY March 26, 1963 K. HENRICHSEN HYDRAULIC PUMP OR MOTOR 5 Sheets-Sheet 4 Filed Sept. 50, 1959 INVENTOR. KNUT HENRICHSEN w flpaw ATTORNEY March 26, 1963 K. HENRICHSEN HYDRAULIC PUMP 0R MOTOR 5 Sheets-Sheet 5 Filed Sept. 50, 1959 I llll 75 FIG. l5

IN V EN TOR. KNUT HENRICHSEN BY 65% EM,

ATTORNEY United States Patent ()1 3,082,696 HYDRAULIC PUMP R MOTOR Knut Henrichsen, Los Angeles, Calif., assignor to North American Aviation, Inc. Filed Sept. 30, 1959, Ser. No. 843,495 9 Claims. (Cl. 103-161) This application is a continuation-in-part of my copending application Serial No. 682,981 which was a continuation-in-part of my application Serial No. 651,240, now abandoned.

This invention pertains to a hydraulic pump or motor operable at high speeds and high fluid pressures. I

The device of this invention relates to a pump or motor of the pintle valve type of considerably improved ethciency, providing a compact lightweight unit of large capacity. The invention includes a means for balancing pressures around the outer surface of the pintle valve to assure that a fluid film is provided between the valve and the rotatable cylinder block. This pressure balance arrangement may include passageways metering fluid from the high pressure port to the surface of the valve adjacent the low pressure port regardless of whether the device is utilized as a pump or as a motor.

Therefore, it is an object of this invention to provide a pump or motor of compact, lightweight design having a large output capacity. 1 t

A further object of this invention is to provide a pump or motor having provisions for minimizing friction and wear.

Another object ofi this invention is to provide a pump or motor having means to balance pressures around the pintle valve to preclude metal-to-metal contact.

A still further object of this invention is the provision of a universal means for balancing the pressures around the pintle valve so that the device of this invention may be operated either as a motor or pump and with either clockwise or counter-clockwise rotation without any necessity for rearrangement of external connections to the device- Yet another object of this invention is to provide simple non-clogging arrangement for providing lubricatiorr between the pintle valve and the cylinder block rotatable.thereon which is equally effective whether the hydraulic device is operated as a pump or motor.

These and other objects will become more apparent when taken in connection with the following detailed description and the accompanying drawings in which:

' FIG. 1 is a top plan view of the exterior of the device of this invention;

FIG. 2 is an axial sectional view of the invention taken along line 2-2 of FIG. 1;

FIG. 3 is a transverse sectional view taken along line 3-3 of FIG. 2, illustrating the relationship of the bearing race, piston-slipper assemblies, cylinder block and pintle valve;

FIG. 4 is a side elevational view of the pintle valve, with the cylinder block shown removed for purposes of clarity;

FIG. 5 is a sectional view taken along line S5 of FIG. 4, illustrating the forces acting on the pintle valve;

FIG. 6 is a fragmentary view, partially in section, showing how the fluid pressures in the high pressure port provide a force on the pintle;

FIG. 7 is a sectional view taken along line 77 of FIG. 4, illustrating the balancing groove and metering pin arrangement;

FIG. 8 is a fragmentary elevational view, partially in section, further illustrating the balancing groove arrangement;

FIG. 9 is a sectional view taken along line 9-9 of 3,082,696 Patented Mar. 26, 1963 "ice FIG. 7, illustrating the fluid pressures resulting from the balancing grooves;

FIG. 10 is a sectional view of the pintle valve taken along line 10-10 of FIG. 4; 1

FIG. 11 is a fragmentary sectional view illustrating the fluid forces resulting from angular misalignment of the cylinder block and pintle valve;

FIG. 12 is a fragmentary elevational view partially in section similar to FIG. 8, showing the balancing groove arrangement for an underbalanced valve;

FIG. 13 is a sectional view taken along line 13-43 of FIG. 12 further illustrating the balancing groove and metering pin design;

FIG. 14 is a fragmentary sectional view taken along line 14-14 of FIG. 13 illustrating the longitudinal fluid pressure distribution on the upper half of an underbalanced pintle valve for normal stable operation as well as for several conditions of pintle-cylinder block eccentricity;

FIG. 15 is an enlarged fragmentary longitudinal sectional view of a second embodiment of a pump pintle showing a modified form of metering pin arrangement;

FIG. 16 is a fragmentary view, partly in section and partly in elevation, showing a simplified arrangement of the second pintle embodiment for supplying pressurized lubricating fluid to the pintle balancing grooves, thereby providing an optimum embodiment permitting use either as a motor or pump;

FIG. 17 is a transverse sectional view of the pintle valve of FIG. 16 taken along line 17-17 in FIG. 16, illustrating the balancing grooves and lubrication feed and metering arrangement;

FIG. 18 is a schematic view illustrating the longitudinal fluidv pressure distribution along the pintle valve of the embodiments of FIGS. 16 and 17 both for stable normal operation as well as when eccentricity exists between the pintle valve and cylinder block.

Referring in particular to FIGS. 1, 2 and 3 of the drawing the device of this invention includes a pintle valve 1 about which cylinder block 2 rotates. Hereinafter the device will be generally described as a pump but it will be clear to those adept in the art that the device has equal utility as a motor when supplied with a pressurized driving fluid.

The pintle valve includes openings 3 and 4 which serve as the inlet and outlet, respectively, when the unit acts as a pump. The pintle valve in the embodiment illustrated also serves as one end of the housing, connecting to main housing section 5 which surrounds the cylinder block. The pintle valve acts as the main bearing for the pump, while bearing 6 also serves to support the cylinder block axially where shaft 7 mates with splines in the block and acts as a power input when the device is used as a pump, or as a power takeoff when employed as a motor. The cylinder block is provided with a plurality of radial cylinders 8 in which piston-slipper assemblies 1t) reciprocate. Each of these assemblies includes a piston portion 11 for engagement with a cylinder, while slipper portion 12 projects beyond the block and includes a spherical outer face 13 which engages complementary spherical bearing race 14 on the inner surface of the main housing. The preferred embodiment of these piston-slipper assemblies forms the subject matter of my copending application Serial No. 682,981. The unit illustrated is of fixed displacement type with bearing race 14 disposed eccentrically with respect to the pintle valve to effect reciprocation of the piston-slipper assemblies as the cylinder block rotates. V v

Pump inlet 3 and outlet 4 connect with passages 16 and 17 which in turn communicate with diametrically opposed ports '18 and 19. The latter extend circumferentially around portions of the lower side and of the upper side of the pintle valve, respectively. Ports 18 and 19 are dimensioned to correspond to the diameter of the cylinder ports for cooperation therewith in pumping the fluid. With the embodiment shown operating as a pump the cylinder block rotates clockwise in the showing of FIG. 3, thereby drawing fluid from inlet 3 into port 18 and thence into the cylinders on the lower half of the pintle valve. The pistons on the upper portion of the pintle valve move inwardly and force the fluid into port 19, through passage 17 and outlet 4. Leakage fluid in the pump case passes through ports 20 and 21, to central passage 22, the outlet 23 of which may be connected to the reservoir of the hydraulic system. The axial location of this return passage assures that any air in the case will be immediately exhausted as the pump rotates.

An important consideration in providing an efficient pump or motor capable of large capacities, high rotation speeds and long life is to assure that a fluid film is maintained between the outer surface of the pintle valve and the inner surface of the cylinder block. In the design illustrated there is only .0002 inch clearance between the valve and the cylinder block, yet a fluid film must be maintained at all times between these two elements. The pump is subject to certain loads and pressures which complicate the problem of providing such a fluid film. As shown diagrammatically in FIG. 5, the cylinders on the top half of the pintle valve provide a downward load having a resultant W passing through the pintle center. This load moves back and forth angularly between the two dotted line positions shown in FIG. 5 as the cylinder block rotates. This occurs because either three or four cylinders will be in communication with port 19, depending upon the rotational position of the cylinder block. The midpoint is offset slightly from the vertical because of the pump eccentricity.

An upward force is exerted at the top half of the pintle opposing W This results from the fluid pressure within port 19 as illustrated in FIG. 6 (in which clearances have been exaggerated) Where curve A depicts the pressure distribution across the top of the pintle. Thus, full pump pressure is exerted in port 19 while the pressure drops off as an essentially straight line across the area between the pintle and the cylinder block to the pump case pressure which will be substantially zero. The resultant W of this pressure always opposes W and moves back and forth in the same manner. In the design shown the high pressure port 19 is sufficiently large so that W is about one-fourth greater than W thereby causing a pintle overbalance urging the lower surfaces of the cylinder block and pintle into contact.

Additional forces are present tending to cause metalto-metal contact between the pintle and the cylinder block. The eccentricity of the slipper race with respect to the pintle causes a force tending to move the cylinder block to the left from the position in FIG. 3, which would cause metal-to-metal contact on the right-hand portion of the pintle. A force urging the cylinder block to the right results from acceleration of the pistons within the cylinders, but this may be either grcater or less than the leftward force depending upon the pump design and rotational speeds. Additionally, if the pump is installed in a rapidly moving vehicle such as an aircraft, gyroscopic forces resulting from high speed maneuvering will tend to misalign the cylinder block and pintle.

The features best seen in FIGS. 7, 8 and 9 overcome these unbalancing forces and assure that a fluid film is maintained. To this end, a pair of balance grooves 29 is provided in the surface of the pintle on one side of the midpoint of port 18 (the vertical line of the pump) arranged to straddle port 18. A similar pair 30 is located on the other side of the vertical of the pintle. Passageways 32 and 33 interconnect high pressure port 19 with the balance grooves. These ports are provided with suitable restrictions such as metering pins 34 and 35 which hold the flow to a predetermined value, depending upon the clearance in the passageways. These metering passageways and the grooves permit fluid from port 19 to provide an additional force at the bottom of the pintle as illustrated in curves B and C of FIG. 9. The groove pressure drops off substantially linearly to case pressure at the edge of the port, and at the edge of the adjacent surfaces of the cylinder block and pintle. The pressures within these grooves provide resultants W and W.,, as shown in FIG. 7. These resultants will balance the difference between forces W and W and proper proportioning of the metering passageway-s will control the rate of fluid flow into the balancing grooves so that concentricity of pintle and cylinder block is maintained.

Additionally, forces W and W counteract other unbalancing forces on the pintle. For example, if the cylinder block tends to move to the left from the position of FIG. 3, which may result from pump eccentricity, this tends to close up grooves 29, while opening up grooves 30. This means that the flow out of grooves 29 will decrease and the pressure therein will rise, while the presusre in grooves 30 decreases. This will move the cylinder block back toward the central position. A similar balancing action takes place if the cylinder block tend to move to the right.

Forces tending to misalign the cylinder block and pintle are counteracted in the manner illustrated diagrammatically in FIG. 11, as well as by the balancing grooves in the bottom of the pintle. If the cylinder block tilts to a position with one edge in contact with the pintle as illustrated in FIG. 11, the pressure curve A will be altered to the shape illustrated from its original symmetrical form shown in dotted lines. By reason of the tilted position of the cylinder block, substantially full pressure will be maintained out to the contacting edge causing the right-hand portion of the curve to increase in area. The raised portion of the block at the left causes a tapered clearance at the left which causes the presusre to drop off non-linearly and reduce the area under that portion of the curve. Resultant W therefore moves to the right and provide a moment tending to move the cylinder block back toward its properly aligned position. Additionally, the tilting of the cylinder block will tend to close up grooves 29 and 30 on the lefthand side of port 18 while opening up the grooves on the right-hand side. This increases the pressure in the grooves 0n the left of the port 18 while decreasing the pressure in the grooves on the right-hand side of the port, thereby also providing a righting moment for returning the cylinder block to a position of alignment;

It is apparent, therefore, that the balancing grooves are located so that they provide fluid forces in directions to overcome any of the unbalancing forces which may be encountered.

By the design described above, it is possible to obtain forces which will maintain a fluid film between the valve and cylinder block for all rotational speeds and conditions so that virtually no wear results. In tests pencil marks made on the surface of the pintle valve have remained intact after millions of revolutions of the cylinder block.

This is possible because the high pressure port 19 is proportioned to give an overbalanced condition for the pintle, which is counteracted by the pressure in the balancing grooves located remote from the high pressure port. In this manner, not only may the pintle overbalance be corrected, but the additional unbalancing forces such as may arise from pump eccentricity, acceleration of the pistons and gyroscopic conditions, also may be offset. If an unbalanced condition were not created deliberately between the high pressure port and the cylinder block, the latter unbalancing forces could not be overcome. In other words, if the high pressure port were dimensioned so that the resultant of its fluid pressure exactly equaled the downward load from the cylinders (i.e., if W equaled W balancing grooves could not be used because they would upset the equilibrium between these two loads. As a result, the additional unbalancing forces from eccentricity, piston acceleration and gyroscopic effect would meet no opposition and metal-to-metal contact would be inevitable.

The principles of this invention may be applied with equal facility to a design where the pintle valve is underbalanced as illustrated in FIGS. 12, 13 and 14. Here the size of the high pressure port 56 is less than the size of port 19 of the previously described embodiment. It is reduced sufficiently in width so that resultant force W from the fluid pressure in port 56 is smaller than resultant force W of the cylinder load on the pintle. Preferably also the width of the cylinder block at the valve is less than in the previous embodiment so that there is a more rapid drop oil? in pressure and consequently a reduced resultant force. The excess of W over W in this design urges the top of the cylinder block inner surface against the top portion of the valve at the area around the high pressure port.

The unbalanced condition is corrected again by means of balancing grooves connecting with the high pressure port. A pair of grooves 57 is provided on the upper surface of the pintle on one side of the midpoint of port 56, arranged to straddle that port. A similar pair 58 is provided on the other side of the midpoint of port 56. Pairs of passageways 59 and 60 interconnect port 56 and the balance grooves, while metering pins 61 and 62 restrict the flow through passageways 59 and. 60', respectively, to a predetermined value. This connection is made through outlet passage 63 which, of course, has the same pressure as port 56. The connection from port 56 to the balancing groove 57 and 58 allows an additional force to be exerted between the upper portion of the pintle valve and the cylinder block. This is illustrated graphically in FIG. 14 where it may be seen that the grooves result in a greater area beneath the pressure curve. The additional force so provided, plus the resultant W may be caused to balance W and by proper proportioning of the metering pins 61 and 62, the rate of flow into the balancing grooves may be controlled to prevent metal-to-metal contact between the block and the pintle. Curve A of FIG. 14 illustrates the normal pressure distribution along the pintle for a balanced concentric condition of the cylinder block and pintle. Curve B illustrates the maximum pressure distribution with a zero clearance between the top of the pintle and the cylinder block; while curve C illustrates the reverse or minimum pressure condition wherein the bottom of the pintle has a zero clearance with the cylinder block and the top clearance is a maximum.

In a manner similar to that for the previously described embodiment, the resultant forces W and W from the balance grooves 57 and 58 extend angularly with respect to the midpoint of the high pressure port and return the pintle to a concentric position with respect to the cylinder block whenever an unbalancing force tends to move it to one side or to cause relative tilting. If the clearance at the grooves is changed, the pressure therein will also vary as with the previously described embodi ment to counteract the unbalancing-force. I

The basic concept, therefore, in providing a fluidfilm between the cylinder block and the valve block is first to create an unbalance between the load imposed by the cylinders on the valve and the opposing load from the fluid in the high pressure port. Then fluid is metered from the high pressure port to the valve surface at a location where additional fluid pressure can be applied to overcome the unbalance between those two loads. This location is selected also so that the additional fluid pressure will counteract any other unbalancing forces present. Within this additional fluid pressure the latter unbalancing forces cannot be offset and metal-to-metal contact will result. Positioning the additional pressure outlets at the valve surface adjacent the inner perimeter of the cylinder block means that when the clearance at the pressure outlet decreases the force exerted will become greater. When the clearance becomes larger, the force is less. Thus, the magnitude of the force from the additional pressure outlets adjusts itself to the requirement at hand.

In some instances, such as for an arrangement like that disclosed in my copending application Serial No. 733,408, now Patent No. 3,051,194 granted August 28, 1962, it may be desirable to have the pintle conduits which communicate the high pressure fluid to the pintle balance grooves fed from the high pressure outlet passage rather than from the high pressure port 19. In such an arrangement, the conduits and metering pins ex tend longitudinally within the pintle 1, as shown in FIG. 15, thus providing greater ease of manufacture. This arrangement lends itself to an improved form of selfcleaning metering pin. Fixed metering pins having narrow restricted orifice sections tend to catch and retain foreign material carried by the hydraulic fluid and thus promote the formation of deposits. Such clogging of the flow passages may be obviated by the floating metering pin arrangement of FIG. 15. In this arrangement metering pin 70 is centered within the conduit 71 located in pintle 1 by means of flanges 72. Flat sides 73 on the flanges form passages for fluid flow. The predetermined diametral clearance between central area 74 of the pin and the walls of conduit 71 provides the required fluid metering restriction. Pin 70 is biased against a bore closure member 75 by spring 76.

In operation fluid enters at 77 from the high pressure port and passes through bore 71 and out bya conduit 78 connected to the pintle balance grooves. Extension 79 on the pin holds it clear of inlet conduit 78 and in sures fluid entry into bore 71. As shown in FIG. 15, pin 70 tends to be displaced axially to the left by the force resulting from the pressure drop through the restricted bore. Spring 76 is designed to resist the displacing force yet permit some degree of movement to dislodge material which otherwise would impair the metering action. Clogging or impairment of the restricted flow passage will cause the pressure differential across the pin to rise, thus disturbing the spring biased pin from its equilibrium position. This will cause the pin to move axially to dislodge the deposit and thereby promote a self-cleaning action.

While the present device can be operated as a pump and also as a motor by supplying pressurized fluid tothe outlet port 4 (with a consequent reversal in direction of rotation), for universal operation of the present device either as a pump or motor and assuming operation as a motor with rotation in the same direction as when it is operated as a pump, pressurized fluid would be supplied to the inlet port 3 and thence through port 18 to the rotating cylinders. Thus, pressure acting on the lower part of the pintle would result in an upwardly directed resultant force passing through the pintle center equal but opposite to that occurring when operated as a pump. To overcome this unbalancing force and assure the maintenance of a fluid film on the upper surface of the pintle, a pair of balancing grooves should be provided on the upper pintle surface on either side of the midpoint of port 19 arranged to straddle the port. Such grooves must be fed from the high pressure source and suitably metered to supply a predetermined pressure to each groove of the upper set of grooves.

Thus, to allow universal operation of the device of this invention, either as a pump or motor and with rotation in either direction, a set of four pressure balancing grooves should be provided on both the upper and lower halves of the pintle valve. Such universal operation, therefore, also requires that four fluid metering bores 'be provided in the pintle in addition to the four such bores heretofore described as required for operation as a pump or as a motor having a reverse direction of rotation. These bores would connect four additional balancing grooves located on the upper surface of the pintle to the inlet passages 16 which would then be supplied with pressurized fluid for motor operation. Suitable check valve means in all eight of the fluid metering bores would be provided to prevent flow reversal during operation as either a motor or a pump. The additional grooves would be disposed on the pintle diametrically opposite the duality of lower groove pairs. To locate four more bores and fluid metering pins within a pintle of the type shown in FIGS. 7 or 15 would introduce extreme complexity into the pintle construction even if sufliicent space were available to allow for such an arrangement. Accordingly, an improved arrangement for producing this desired result is shown in FIGS. 16 and 17. This is shown as applied to a pintle having longitudinally extending metering bores, although it could also be utilized with an arrangement of the type shown in FIG. 7. In this arrangement only two pintle bores are required to supply the grooves and allow universal operation either as a pump or motor with either clockwise or counterclockwise rotation. The two pintle bores replace the eight bores required for universal pump or motor operation in the previous device. These bores are relatively unrestricted, having no metering pin therein, thereby minimizing any fouling and clogging which may occur, particularly at elevated temperatures, when such metering pins are used in the bores.

As shown in FIGS. 16 and 17, pump cylinder block 80 is rotatably supported upon pintle 81, which contains two longitudinally extending bores 82 and 83. Considering clockwise rotation of the device operating as a pump, bore 82 connects to the pump outlet port, while bore 83 communicates with the pump inlet port. In the corresponding mode of motor operation, with clockwise rotation, bore 83 transmits the pressurized fluid from the inlet port of the device. Bore 82 and 83 contain check valves 84 and 85, respectively, therein preventing reverse flow. Thus, while the unit may be utilized either as a pump or motor and may be run in either direction, pressure will always be supplied to the correct pintle balancing grooves to balance the unbalanc-ing forces and maintain the pintle and cylinder block in concentricity. The check valves prevent flow from the high pressure region to the low pressure region regardless of whether the unit is operated as a pump or motor.

Bores 82 and 83 interconnect with a conduit arrangement 97 lying in a transverse plane of the pintle and comprising chordwise extending bores 86, 87 and 88. These bores terminate in radially extending bores 89, 90, 91 and 92, which communicate with shallow metering grooves or channels 95 located at quadrature points on the circumference of the pintle. These shallow metering grooves 95 are of the order of .001650 inch in depth and are interconnected around the circumference of the pintle by means of the much deeper pressure balancing grooves 96 which are also located in a quadrature relationship, and which are of the order of .032 inch in depth. This system of passageways supplies pressurized fluid to the grooves in a relatively unrestricted manner whereby full pressure may be supplied to the grooves 95 which are of a predetermined size and length to eflectively meter the fluid pressure to the grooves 96, whereby the desired pressure balancing relationship between the cylinder block and pintle is obtained. A second transverse circumferential groove arrangement 8 comprising a similar series of chordwise and radially extending passageways is disposed on the opposite side of the pintle pressure port. Groove arrangement 98 is a duplicate of groove arrangement 97 and is connected thereto by means of short longitudinally extending bores 93 and 94 which interconnect the two planar systems of fluid supplying passageways.

FIG. 18 illustrates the pressure distribution in the region of the balancing grooves under various conditions of clearance between the pintle and cylinder block, with the upper part being subjected to the high side pressure, either as a pump or motor. Curve A illustrates the pressure distribution in the region of the pintle ports and across the balancing groove, with the pintle and cylinder block in a concentric relation. Curve B illustrates the pressure distribution with a zero clearance between the top of the pintle and the cylinder block. Curve C illustrates the reverse condition wherein the bottom of the pintle has a zero clearance with the cylinder block. It will be noted that the groove pressure drops off substantially linearly to case pressure at the edge of the pintle low pressure port, and at the edge of the adjacent surfaces of the cylinder block and pintle. From the groove pressure of the top groove, the pressure rises to the pressure in the pintle high pressure port. The pressures within these grooves can be made to provide resultant forces which will counteract the overbalance and by proper proportioning of the metering passageways, maintain the cylinder block vertically and axially concentric with the cylinder.

It will be seen by the foregoing, therefore, that I have provided an improved hydraulic device incorporating features which materially reduce the wear of the unit and greatly increase its efliciency and capacity.

The foregoing detailed description is to be clearly understood as given by way of illustration and example, the spirit and scope of this invention being limited only by the appended claims.

I claim:

1. A hydraulic device comprising a pintle valve; a cylinder block in engagement with and rotatable relative to said pintle valve, said cylinder block having a plurality of cylinders therein, said pintle valve having a high pressure and a low pressure port cooperating with said cylinders; a piston-slipper assembly reciprocative in each of said cylinders; a bearing race engaged by the slipper portions of said piston-slipper assemblies, said bearing race being positioned to cause reciprocation of said pistonslipper assemblies upon such rotation of said cylinder block, said high pressure port being dimensioned such that upon rotation of said cylinder block the fluid therein exerts a force on said cylinder block unequal to the force of said cylinder block on said valve whereby a predetermined unbalanced force results; pressure balancing means comprising a plurality of grooves extending at least partially around the circumference of said pintle valve and lying substantially in each of two radially transverse planes located one on each side of said high pressure and low pressure ports; conduit means communicating fluid pressure from said high pressure port to said grooves, said conduit means including separate restricted passage means individually communicating a reduced fluid pressure to each of said pressure balancing grooves suflicient to overcome the unbalanced force between said cylinder block and said pintle valve, said pressur balancing grooves being predeterminately positioned on the circumference of the pintle so that the resultant force of the reduced fluid pressure communicated thereto counteracts the unbalanced force, said separate restricted passage means further providing a higher reserve fluid pressure which is automatically selectively applied to certain of the individual grooves to thereby exert an increasingly greater force if the dimensional clearance between the pintle and cylinder block tends to decrease in the region adjacent such certain grooves whereby the cylinder block and pintle valve are maintained in a concentric dynamically table relation.

2. A hydraulic device as recited in claim 1, wherein said high pressure port is proportioned so that the fluid therein exerts a greater force on said cylinder block than the force exerted by said cylinder block on said pintle valve thereby creating an overbalanced force tending to bring the lower surface of said pintle valve into contact with the rotating cylinder block and wherein each plurality of grooves lying substantially in each of the radially transverse planes on each side of said high and low pressure ports comprises two grooves on the lower half of said pintle valve equiangularly spaced on the pintle valve oircumference with respect to an axially extending plane passing vertically through said high and low pressure port means.

3. A hydraulic device as recited in claim 2 wherein said two grooves on the lower half of said pintle valve are symmetrical about lines extending at 45 from each side of the axially extending plane passing vertically through said high and low pressure port means.

4. A hydraulic device as recited in claim 1 wherein said high pressure port is proportioned so that the fluid therein exerts a lesser pressure on said cylinder block than the force exerted by said cylinder block on said pintle valve thereby creating an underbalanced force tending to bring the rotating cylinder block into contact with the upper surface of said pintle valve, in which each of said plurality of grooves lying substantially in each of the radially transverse planes on each side of said high and low pressure ports comprises two grooves on the upper half of said pintle equiangularly spaced on the pintle circumference with respect to an axially extending plane passing vertically through said high and low pres sure ports.

5. A hydraulic device as recited in claim 1 wherein each of said plurality of grooves lying substantially in each of the radially transverse planes on each side of said high and low pressure ports comprises four grooves located in quadrature relation on the surface of said pintle valve.

6. A hydraulic device as recited in claim 5 wherein said separate restricted passage means individually communicating a reduced fluid pressure to each of said pressure balancing grooves comprises metering grooves on the surface of said pintle valve.

7. A hydraulic device comprising a valve member; a cylinder block in engagement with and rotatable relative to said valve member, said cylinder block having a plurality of chambers therein; a piston-slipper assembly reciprocative in each of said chambers; a bear-ing race eccentric to said cylinder block engaged by slipper portions of piston-slipper assemblies to cause reciprocation of the same upon rotation of the cylinder block, said valve member having high pressure and low pressure fluid passage means therein communicating with said chambers and the exterior of said hydraulic device, said cylinder block being acted on by predetermined unbalancing forces tending to shift the same out of concentricity with said valve member in a predetermined direction upon rotation of the cylinder block; a plurality of grooves disposed on the circumference of said valve member in each of two radially transverse planes which are spaced an equal distance on either side of the center line of said cylinder block, said grooves being located about the circumference of the valve member so as to provide fluid force compoments in opposition to the cylinder block unbalancing forces; metering conduits interconnecting each groove means and said high pressure fluid passage means including separate metering means for individually and separately supplying fluid to each of said grooves at a lesser pressure than the pressure in said high pressure fluid passage means, said fluid force components acting to counteract such predetermined unbalancing forces around the circumference of said valve member and maintain said cylinder block and said valve member in concentric relation, said separate metering means further providing a reserve pressure individually available to each groove to exert a greater than normal force to automatically resist and counteract any further dynamic unbalancing forces tending to cause either radial or axial eccentricity between the valve member and the cylinder block.

8. A hydraulic device comprising a pintle valve membet; a cylinder block in engagement with and rotatable relative to said pintle valve member, said cylinder block having a plurality of chambers therein; a piston-cylinder assembly reciprocative in each of said chambers; a bearing race eccentric to said cylinder block engaged by slipper portions of said piston-slipper assemblies to effect reciprocation of the same upon rotation of the cylinder block, said pintle valve member having high and low pressure ports and passageways therein which form high and low pressure conduit arrangements providing communication between said chambers and the exterior of said hydraulic device, said cylinder block having predetermined unbalancing forces acting thereon tending to shift the same out of concentric alignment with said pintle valve member upon rotation of the cylinder block; a plurality of grooves disposed on the circumference of said pintle valve member in each of two radially transverse planes which are spaced an equal distance on either side of the center line of said cylinder block, said grooves being located around the circumference of the pintle valve member so as to provide a force opposite to and compensating said unbalancing forces, each of said grooves communicating with said high pressure conduit arrangement by separate metering passageways which individually supply fluid flow to the grooves at individually reduced pressures; each of said plurality of grooves being circumferentially arranged to provide a resultant hydraulic force having components acting along vertical and horizontal axes of one of the pintle valve member transverse radial planes, while said plurality of grooves in each of said radially transverse planes provide force components axially along the pintle valve member, said force components automatically counteracting such predetermined unbalancing forces as well as any unstable dynamic forces both axially and around the circumference of said pintle valve member thereby maintaining the cylinder block and valve member in concentric relation.

9. A device as recited in claim 8, in which said separate metering passageways comprise circumferentially extending channels on the surface of said pintle valve member interconnecting said grooves.

References Cited in the file of this patent UNITED STATES PATENTS 1,081,810 Carey Dec. 16, 1913 1,878,862 Landenberger Sept. 20, 1932 2,205,913 Stacy June 25, 1940 2,328,717 Gl-asner Sept. 7, 1943 2,416,638 Morton Feb. 25, 1947 2,426,588 Benedek Sept. 2, 1947 2,454,418 Zimmermann Nov. 23, 1948 2,769,393 Oardillo et a1. Nov. 6, 1956 2,901,979 Henrichsen Sept. 1, 1959 2,977,891 Bishop Apr. 4, 1961 

1. A HYDRAULIC DEVICE COMPRISING A PINTLE VALVE; A CYLINDER BLOCK IN ENGAGEMENT WITH AND ROTATABLE RELATIVE TO SAID PINTLE VALVE, SAID CYLINDER BLOCK HAVING A PLURALITY OF CYLINDERS THEREIN, SAID PINTLE VALVE HAVING A HIGH PRESSURE AND A LOW PRESSURE PORT COOPERATING WITH SAID CYLINDERS; A PISTON-SLIPPER ASSEMBLY RECIPROCATIVE IN EACH OF SAID CYLINDERS; A BEARING RACE ENGAGED BY THE SLIPPER PORTIONS OF SAID PISTON-SLIPPER ASSEMBLIES, SAID BEARING RACE BEING POSITIONED TO CAUSE RECIPROCATION OF SAID PISTONSLIPPER ASSEMBLIES UPON SUCH ROTATION OF SAID CYLINDER BLOCK, SAID HIGH PRESSURE PORT BEING DIMENSIONED SUCH THAT UPON ROTATION OF SAID CYLINDER BLOCK THE FLUID THEREIN EXERTS A FORCE ON SAID CYLINDER BLOCK UNEQUAL TO THE FORCE OF SAID CYLINDER BLOCK ON SAID VALVE WHEREBY A PREDETERMINED UNBALANCED FORCE RESULTS; PRESSURE BALANCING MEANS COMPRISING A PLURALITY OF GROOVES EXTENDING AT LEAST PARTIALLY AROUND THE CIRCUMFERENCE OF SAID PINTLE VALVE AND LYING SUBSTANTIALLY IN EACH OF TWO RADIALLY TRANSVERSE PLANES LOCATED ONE ON EACH SIDE OF SAID HIGH PRESSURE AND LOW PRESSURE PORTS; CONDUIT MEANS COMMUNICATING FLUID PRESSURE FROM SAID HIGH PRESSURE PORT TO SAID GROOVES, SAID CONDUIT MEANS INCLUDING SEPARATE RESTRICTED PASSAGE MEANS INDIVIDUALLY COMMUNICATING A REDUCED FLUID PRESSURE TO EACH OF SAID PRESSURE BALACING GROOVES SUFFICIENT TO OVERCOME THE UNBALANCED FORCE BETWEEN SAID CYLINDER BLOCK AND SAID PINTLE VALVE, SAID PRESSURE BALANCING GROOVES BEING PREDETERMINED POSITIONED ON THE CIRCUMFERENCE OF THE PINTLE SO THAT THE RESULTANT FORCE OF THE REDUCED FLUID PRESSURE COMMUNICATED THERETO COUNTERACTS THE UNBALANCED FORCE, SAID SEPARATE RESTRICTED PASSAGE MEANS FURTHER PROVIDING A HIGHER RESERVE FLUID PRESSURE WHICH IS AUTOMATICALLY SELECTIVELY APPLIED TO CERTAIN OF THE INDIVIDUAL GROOVES TO THEREBY EXERT AN INCREASINGLY GREATER FORCE IF THE DIMENSIONAL CLEARANCE BETWEEN THE PINTLE AND CYLINDER BLOCK TENDS TO DECREASE IN THE REGION ADJACENT SUCH CERTAIN GROOVES WHEREBY THE CYLINDER BLOCK AND PINTLE VALVE ARE MAINTAINED IN A CONCENTRIC DYNAMICALLY STABLE RELATION. 